Disability Statistics with a Caveat

Statistics play an important role in our society. They are used to determine societal needs and wants and to find solutions to meeting those needs and wants. For example, we use statistics to decide where to put a shopping mall, what health care treatment is most successful, how many schools to build in a certain area, what products and services consumers will buy, and what vehicles provide the best combination of safety and gas mileage. Laws, funding, policies, and programs are also born from statistics. Therefore, statistics need to be consistent, reliable, and valid to reassure a skeptical public that their elected representatives are allocating appropriate time, effort, and money to meeting and balancing societal needs.

Although we want to be able to trust statistics, sometimes they seem somewhat inconsistent and mysterious. Some of the most confusing statistics are disability-related, mostly because there is no one, clear definition of disability; the definition of disability is different for federal and state laws, public programs, insurance plans, and organizations. As a result, it is easy to become lost trying to find accurate statistics regarding individuals with disabilities.

For example, the two most prominent definitions of disability are based on the Social Security Administration's disability benefits programs, Social Security disability insurance (SSDI) and Supplemental Security Income (SSI), and the Americans with Disabilities Act (ADA):

Under Social Security programs, disability is based on an individual's inability to work. An individual is considered disabled under Social Security rules if he/she cannot do work that was done before. The Social Security Administration (SSA) must then decide that an individual cannot adjust to other work because of medical condition(s). A disability must also last or be expected to last for at least one year or to result in death.

Under the ADA, the term "disability" is defined in general terms rather than with a list of medical conditions. The definition of disability includes: (1) a person who has a physical or mental impairment that substantially limits one or more major life activities, (2) a person with a record of a physical or mental impairment that substantially limits one or more major life activities, and (3) a person who is regarded as having a physical or mental impairment that substantially limits one or more major life activities.

These two very different definitions of disability contribute to what are arguably the most disputed disability statistics: 1) the number of people with disabilities, and 2) the employment rate of people with disabilities. In addition to the variations resulting from the use of different definitions of disabilities, surveys that yield disability data may provide variations in results because:

Sample size is limited.

Individuals living in institutions, college dormitories, and other group quarters are often excluded.

Proxies may be allowed to answer.

Individuals are required to self-report disability.

Delivery among interviewers may be inconsistent.

Question design, including the definition of disability, varies among surveys and from time period to another.

Regardless of variations from the data and the somewhat controversial status of disability statistics, statistics can be very helpful and powerful when delineating needs and looking for solutions. To select a disability statistic that meets your needs, follow a five step process:

Determine why you need the statistic. For example, are you looking for employment statistics? If so, it is unlikely that the SSA beneficiary data will answer your question.

Locate a reliable source. For example, the Census Bureau provides information on the advanced methodology used to collect data for the ACS.

Understand the definition of disability used to collect data. For example, the SSA and ADA are based on very different definitions.

Determine whether the variables included in the statistic have changed over time. For example, employment rates are higher when they include part-time employment.

Provide resources for replication. For example, a statistic should be reported with enough information that it allows the reader to replicate the results. As with any vehicle for change, the user must be aware of how the data were gathered, analyzed, and reported and understand that all statistics come with a caveat.